lldb: Switch from llvmPackages_latest to llvmPackages

[primeos]

I don't think this was ever supposed to use llvmPackages_latest.
Now it's consistent with the other LLVM attributes (lld, llvm, etc.).

Motivation for this change

Noticed this while checking #116629 (comment) (cc @ggreif) now https://discourse.nixos.org/t/llvm-lldb-11-in-20-09-vs-unstable/10837 makes sense as well.

Things done

• Tested using sandboxing (nix.useSandbox on NixOS, or option sandbox in nix.conf on non-NixOS linux)
• Built on platform(s)
  • NixOS
  • macOS
  • other Linux distributions
• Tested via one or more NixOS test(s) if existing and applicable for the change (look inside nixos/tests)
• Tested compilation of all pkgs that depend on this change using nix-shell -p nixpkgs-review --run "nixpkgs-review wip"
• Tested execution of all binary files (usually in ./result/bin/)
• Determined the impact on package closure size (by running nix path-info -S before and after)
• Ensured that relevant documentation is up to date
• Fits CONTRIBUTING.md.

[primeos]

Seems like this was intentional: f396492 (#99365).
@Mic92 the current approach seems very inconsistent to me do we really want it to default to the latest version?

[primeos]

For some more context:

  clang = llvmPackages.clang;
  clang-manpages = llvmPackages.clang-manpages;
  lld = llvmPackages.lld;
  llvm = llvmPackages.llvm;
  llvm-manpages = llvmPackages.llvm-manpages;

But I just noticed the following is also somewhat inconsistent (though here it makes way more sense IMO):

  clang-tools = callPackage ../development/tools/clang-tools {
    llvmPackages = llvmPackages_latest;
  };

  clang-analyzer = callPackage ../development/tools/analysis/clang-analyzer {
    llvmPackages = llvmPackages_latest;
    inherit (llvmPackages_latest) clang;
  };

IMO all of the aliases (i.e. the attributes that reference llvmPackages.XYZ or llvmPackages_latest.XYZ) should point to the same version.

[nixos-discourse]

This pull request has been mentioned on NixOS Discourse. There might be relevant details there:

https://discourse.nixos.org/t/llvm-lldb-11-in-20-09-vs-unstable/10837/4

[Mic92]

Seems like this was intentional: f396492 (#99365).
@Mic92 the current approach seems very inconsistent to me do we really want it to default to the latest version?

From my understanding we cannot use the latest llvm/clang version because the ecosystem does not work with it, but why does this apply to lldb? LLVM 7 was released in 2018, which is three years ago.

[primeos]

From my understanding we cannot use the latest llvm/clang version because the ecosystem does not work with it, but why does this apply to lldb?

It doesn't apply to lldb, I only mind that some LLVM attributes point to llvmPackages_latest and others to llvmPackages (which is inconsistent and could cause unexpected issues). The alternative, which might be even better, would be to switch everything to llvmPackages_latest instead.

The important part for the Nixpkgs ecosystem is the following:

  llvmPackages = recurseIntoAttrs (with targetPlatform;
    if isDarwin then
      llvmPackages_7
    else if isFreeBSD then
      llvmPackages_7
    else if isLinux then
      llvmPackages_7
    else if isWasm then
      llvmPackages_8
    else
      llvmPackages_latest);

IMO most stuff in Nixpkgs should use stdenv = llvmPackages.stdenv or e.g. llvmPackages.llvm (instead of llvm - it might actually be best to move those into pkgs/top-level/aliases.nix).

[primeos]

So basically the question is do we point the aliases for the individual LLVM packages to llvmPackages or llvmPackages_latest?
I guess llvmPackages_latest would make more sense (i.e. I'd need to change this PR) but I'm fine with both as long as it isn't a mix of both (which IMO only causes unnecessary problems and confusion).

I'd also like to move them to pkgs/top-level/aliases.nix to ensure they aren't used in Nixpkgs (they're convenient for users but IMO packages in Nixpkgs should use (mainly) llvmPackages.stdenv). Any objections?

[Mic92]

So basically the question is do we point the aliases for the individual LLVM packages to llvmPackages or llvmPackages_latest?
I guess llvmPackages_latest would make more sense (i.e. I'd need to change this PR) but I'm fine with both as long as it isn't a mix of both (which IMO only causes unnecessary problems and confusion).

I'd also like to move them to pkgs/top-level/aliases.nix to ensure they aren't used in Nixpkgs (they're convenient for users but IMO packages in Nixpkgs should use (mainly) llvmPackages.stdenv). Any objections?

That makes sense to me.

[primeos]

I tried to implement #116736 (comment) in #118076 but unfortunately llvm and clang are used much more than I've expected.